A federal appeals court said the government can't restrict advertising by pharmacists who sell so-called drug compounds -- specialized mixtures of drugs for individual patients.

The decision pitted the free-speech rights of pharmacists against a federal law aimed at restricting advertising of compounds, which require a doctor's prescription but aren't subject to the Food and Drug Adminstration's drug-approval process.

Citing previous court decisions, the U.S. Court of Appeals for the Ninth Circuit in San Francisco noted that "government prohibitions of truthful commercial messages are 'particularly dangerous' and deserve 'rigorous review.'"

A spokesman for the FDA, which was charged with enforcing prohibitions on compound ads, said it was evaluating the decision.

Compounding involves the mixing of ingredients from different drugs to create a specialized medication for an individual patient -- such as a person allergic to an ingredient in a mass-produced product. Under a law passed by Congress in 1997, pharmacists who mix drugs could advertise the fact that they did so, but were prohibited from advertising specific compounds that they may specialize in.

The government has contended that restrictions on ads for compounds were an attempt to balance the specialized needs of individual patients with the protection of the broader public by "preventing widespread distribution of compounded drugs."

In an opinion that upheld a lower-court ruling, Judge Cynthia Holcomb Hall wrote that "the government neither explains nor supports" its contention that wider distribution of compounded drugs would endanger the public. "In fact, most of the evidence runs to the contrary," she wrote, noting that "compounding is not only legal under state law, but most states require their pharmacists to know how to compound."

The government offered "no evidence demonstrating that its restrictions would succeed in striking the balance it claims is a substantial interest, or even would protect the public health," Judge Hall wrote.

The FDA regulates other types of drug advertising and is continually trying to balance the promotional rights of companies with its obligation to protect the public from unsafe substances. Two years ago, the agency lost a similar case involving drug-company representatives promoting off-label uses of particular drugs.

"If it's a legal activity -- and compounding is legal -- then you can legally promote it," said Marc Scheineson, a former FDA official who is currently a Washington lawyer representing EthicAd, a nonprofit organization in Atlanta developing standards for direct-to-consumer drug ads.